Deep reinforcement learning agents are often misaligned, as they over-exploit early reward signals. Recently, several symbolic approaches have addressed these challenges by encoding sparse objectives along with aligned plans. However, purely symbolic architectures are complex to scale and difficult to apply to continuous settings. Hence, we propose a hybrid approach, inspired by humans' ability to acquire new skills. We use a two-stage framework that injects symbolic structure into neural-based reinforcement learning agents without sacrificing the expressivity of deep policies. Our method, called Hybrid Hierarchical RL (H^2RL), introduces a logical option-based pretraining strategy to steer the learning policy away from short-term reward loops and toward goal-directed behavior while allowing the final policy to be refined via standard environment interaction. Empirically, we show that this approach consistently improves long-horizon decision-making and yields agents that outperform strong neural, symbolic, and neuro-symbolic baselines.
Figures & tables
Figure 1: Deep reinforcement learning policies are often misaligned , exemplified on neural PPO agents. Although the oxygen is running low in Seaquest (left) and the goal in Kangaroo (right) is to go up, PPO agent fails to choose the optimal actions (in green). Instead, they focus on immediate rewards, e.g., keep attacking enemies.
Figure 2: Overview of the framework. Through logic-informed pretraining, H 2 RL embeds logic priors directly into neural policies, thereby addressing the deep policy misalignment issue. H 2 RL provides a two-stage training paradigm. In the first stage, the deep policy is jointly trained with the logic manager and the gating module (referred to as deep policy pretraining). In the second stage, the deep policy is further trained through direct interaction with the environment (referred to as deep policy post-training). See Sec. 3 for details.
Figure 3: Leveraging logic-informed pretraining, H 2 RL with its variants (bolded), outperforms baselines on challenging ALE tasks ( Seaquest , Kangaroo , and DonkeyKong ) with long-horizon dependencies and reward traps. Although DQN and PPO achieve high returns in Kangaroo , their learned policies remain misaligned; see Sec. 4 (RQ1 and RQ3) for details. Episodic returns are averaged over 12 environments (with 200 runs per environment). Results are presented on a log scale to normalize for the disparate reward magnitudes across games.
H 2 PPO +
PPO
H 2 DQN +
DQN
H 2 C51 +
C51
Seaquest
1802 ± 400
3247 ± 881
1966 ± 903
3259 ± 1001
2774 ± 1367
4381 ± 1988
Kangaroo
2754 ± 2626
14592 ± 491
114665 ± 16932
14822 ± 1810
8193 ± 5928
13854 ± 1021
DonkeyKong
87780 ± 32786
4536 ± 296
6887 ± 1765
3205 ± 988
183645 ± 107378
3393 ± 721
Table 1: H 2 RL serves as a universal pretraining substrate for on-policy and off-policy deep RL methods. Shown are the means of the episodic return (averaged over 12 environments, 200 runs per environment) with the std of the pretrained and base policy. Although DQN and PPO achieve high returns in Kangaroo , their learned policies remain misaligned; Details see Sec. 4 (RQ3).
PPO
DQN
C51
hReason
H 2 PPO
H 2 DQN +
H 2 C51 +
Floor 2
0% ± 0%
0% ± 0%
0% ± 0%
100% ± 0%
100% ± 0%
100% ± 0%
100% ± 0%
Floor 3
0% ± 0%
0% ± 0%
0% ± 0%
30% ± 20%
60% ± 10%
100% ± 0%
100% ± 0%
Floor 4
0% ± 0%
0% ± 0%
0% ± 0%
30% ± 10%
50% ± 10%
100% ± 0%
100% ± 0%
Table 2: H 2 RL mitigates policy misalignment via logic-informed pretraining for on-policy and off-policy deep RL methods. The table reports success rates for reaching different floors in Kangaroo for agents pre-trained using H 2 RL, its base variant, and the logic manager (hReason). Success rates averaged over 5 seeds, with 6 runs per seed.
H 2 PPO
PPO
hPPO
hReason
exPPO
Seaquest
2812 ± 1477
3247 ± 881
1906 ± 628
1281 ± 963
1848 ± 34
Kanga./Succ.
5351 ± 4132 / 0.6 ± 0.1
14592 ± 491 / 0
10601 ± 914 / 0
2238 ± 2140 / 0.3 ± 0.2
14247 ± 1085 / 0
DonkeyKong
33657 ± 14578
4536 ± 296
418 ± 139
905 ± 1335
4268 ± 249
Table 3: The synergy between the logic and neural modules is crucial to H 2 RL’s improved performance. As an ablation study, we compare H 2 PPO (the default H 2 RL) with PPO (neural-only), hPPO (neural manager), hReason (logic manager), and exPPO (PPO with extended inputs) on Seaquest , Kangaroo , and DonkeyKong . The table reports the average episodic returns and success rates for reaching the third floor in Kangaroo . For details, see Sec. 4 (RQ3).
Figure 4: H 2 RL effectively leverages logic reasoning in continuous action spaces and improves deep agents’ performance. We compare H 2 RL with methods applicable to continuous action space on the Kangaroo and DonkeyKong tasks in CALE, where H 2 RL consistently outperforms these baselines. Details see Sec. 4 : RQ4.
Table 9: Hyperparameters used when training the models.
Layer
Configuration
Convolutional
Conv2d(4, 32, 8, stride=4)
ReLU
Convolutional
Conv2d(32, 64, 8, stride=2)
ReLU
Convolutional
Conv2d(64, 64, 3, stride=1)
ReLU
Appendix
Table 10: Pixel State Backbone Architecture
Layer
Configuration
Fully Connected
Linear( Nin , 512)
ReLU
Fully Connected
Linear(512, 120)
ReLU
Fully Connected
Linear(120, Nout )
Appendix
Table 11: Object-Centric Backbone Architecture
H 2 RL
PPO
hPPO
hReason
Kangaroo (cont.)
84665 ± 49767
1785 ± 72
19854 ± 18586
557 ± 167
DonkeyKong (cont.)
10818 ± 7431
3836 ± 530
991.0 ± 446
542 ± 975
Appendix
Table 12: H 2 RL outperforms other compared baselines in the Continuous Atari learning environment (CALE). Reward comparison of H 2 RL against other baseline methods which can work in the continuous action space versions of Kangaroo and DonkeyKong.
H 2 RL ++
H 2 RL +
H 2 RL
PPO
NUDGE
Seaquest
4759 ± 1004
1802 ± 400
2812 ± 1477
3247 ± 881
63 ± 18
Kangaroo
131842 ± 1221
2754 ± 2626
5148 ± 3950
14592 ± 491
404 ± 230
DonkeyKong
216793 ± 125655
87780 ± 32786
33690 ± 14565
4536 ± 296
21 ± 43
BlendRL
Option-critic
hDQN
hPPO
hReason
Seaquest
117 ± 62
38 ± 19
112 ∗
1906 ± 628
1186 ± 930
Appendix
Table 13: H 2 RL outperforms other compared baselines in the classical Atari Learning environment. Although PPO and hPPO achieve relatively high scores in Kangaroo, their improvements stem from policy misalignment. We evaluate H 2 RL against other methods in Kangaroo, Seaquest, and DonkeyKong. ∗ Due to instability during evaluation, we report the maximum performance achieved by hDQN during training as a representative metric.
Environment
Modification
Description
Seaquest
random_start
randomize the starting position of the player
random_surfacing
set the player to a random position when reaching the surface
random_lane
set the starting position of the player in one of the 4 lanes where enemies and divers spawn
disable_underwater_enemies
prevent all underwater enemies from appearing in the game
disable_enemies
prevent all enemies from appearing in the game
unlimited_collected_diver
always set the amount of collected divers to 1
Appendix
Table 14: A list of modifications for each environment.
Environment
Option
Applied modifications
Seaquest
get_air, deliver_diver
random_start
disable_underwater_enemies
unlimited_collected_diver
empty_divers_automatically
random_surfacing
enable_surface_enemies
Appendix
Table 15: A list of modifications used when training options in each environment.
Environment
Option
Reward function
Seaquest
get_air, deliver_diver
+1.5 when player is at the surface
get_diver
+1 when player collects a diver
shoot_enemy/wait_in_line
+1 when the player shoots an enemy
-10 when the player moves up or down
Kangaroo
ascend
+20 when player reaches certain positions
deal_with_enemies
+1 when the player obtains a score from punching an enemy
Appendix
Table 16: A list of reward functions used when training options in each environment.